VF650 super charger only making 2.5psi..?

[Compman]

I finally figured out how to put my P3 gauge in English units & while doing a highway pull the psi did not go over 2.5psi..

I thought the car felt sluggish.. I guess this explains it.

What are the causes for a super charger to be making this low boost??

I'm familiar with turbos but I'm new to the supercharger world. I know it operates off the belt so there is no "boost controller"

So I was thinking vacuum leak? Or a blown supercharger??

[Doc Oc]

Could be an issue with the bypass valve allowing it to open when the boost starts to climb.

Possibly belt slippage too if your tensioner isn't tight enough.

What kind of vacuum are you pulling according to the gauge? You positive it's not the p3 hookup?

[CIFUM3]

Ima go with a vacuum leak

[Compman]

Originally Posted by Doc Oc

Could be a vacuum line issue on the bypass valve allowing it to open when the boost starts to climb.

Possibly belt slippage too if your tensioner isn't tight enough.

What kind of vacuum are you pulling according to the gauge? You positive it's not the p3 hookup?

At idle it's around 17-18. Without the air conditioner turned on.

The p3 gauge is hooked up directly to the OBD2 port. So it should get a false reading.. Right??

Where is the by pass valve located? How does it work?

[Compman]

I did some quick research. The bypass valve is the BOV type thing hooked onto the manifold?

[Compman]

Hmmm this morning it was rock solid at -21.0... I didn't do a pull to see if it's still at 2.5psi.

I really want to get this solved. I went to the quarter mile last night and ran a 12.8. Broke my heart

[Doc Oc]

Originally Posted by Compman

I did some quick research. The bypass valve is the BOV type thing hooked onto the manifold?

Yup, it's just like a bov on a turbo car.

While I have a p3, I don't have a SC so I don't know how it measures boost. Iirc, it came with a hookup adapter for boost no? I didn't think you got the boost readings through the obd2 port?

[Doc Oc]

Originally Posted by Compman

Hmmm this morning it was rock solid at -21.0... I didn't do a pull to see if it's still at 2.5psi.

I really want to get this solved. I went to the quarter mile last night and ran a 12.8. Broke my heart

What kind of mph did you get?

[Compman]

I bought the car with these mods already installed so I don't know exactly how the p3 gauge is reading boost.

I'll definitely look into it though.

My MPH was 114. The car just does not feel fast at all. I have my buddy a ride who had a stock e92 and he said my car doesn't really feel much faster then his car was. ?

I sold my RB turbo'd 335 for this thing lol. I ran 11.5 in the 335! With a factory open differential!! Sloow 2nd gear launch. 1 wheel wonder!!

Thanks for helping me out.

[XxMerlinxX]

Sounds like a boost leak somewhere. Start looking at all of your hoses for either a loose hose or a hose with a crack in it. Check your BOV as well, take it off to make sure the o-rings are intact and then fasten it back in place.

[Compman]

Originally Posted by XxMerlinxX

Sounds like a boost leak somewhere. Start looking at all of your hoses for either a loose hose or a hose with a crack in it. Check your BOV as well, take it off to make sure the o-rings are intact and then fasten it back in place.

Will do. I'll report back with my findings. Also the vacuum line that's connected to the BOV goes into an adapter to a huge vacuum line and sneaks under the intake manifold.

Is that the correct routing?

[Doc Oc]

Originally Posted by Compman

I bought the car with these mods already installed so I don't know exactly how the p3 gauge is reading boost.

I'll definitely look into it though.

My MPH was 114. The car just does not feel fast at all. I have my buddy a ride who had a stock e92 and he said my car doesn't really feel much faster then his car was. ?

I sold my RB turbo'd 335 for this thing lol. I ran 11.5 in the 335! With a factory open differential!! Sloow 2nd gear launch. 1 wheel wonder!!

Thanks for helping me out.

Yeah, that's no good. My best run was 12.9@112 the only time I went and that was before mods.

Might seem obvious but check that the pipe between blower and manifold is secure at both ends. Had a sc'd vette not too long ago that came back from a clutch change running like crap and making no boost. Turns out the intake pipe had slid off the throttle body.

[Compman]

Originally Posted by Doc Oc

Yeah, that's no good. My best run was 12.9@112 the only time I went and that was before mods.

Might seem obvious but check that the pipe between blower and manifold is secure at both ends. Had a sc'd vette not too long ago that came back from a clutch change running like crap and making no boost. Turns out the intake pipe had slid off the throttle body.

Okay yeah will do. I'm going to take the intake pipe off as well. Make sure there's nothing stuck in there.

I hope the supercharger isn't blown. It is loud at idle. Also when I rip it hard a little bit of oil splurges out of the bolt on the right. Is that normal??

I attached a pic

[mkPOTO]

yeah check for a boost leak. I have not been the happiest person with my P3 gauge. They also have a way to calibrate it as well. I would do a leak test and see if you hear any leaks.

[Compman]

Originally Posted by mkPOTO

yeah check for a boost leak. I have not been the happiest person with my P3 gauge. They also have a way to calibrate it as well. I would do a leak test and see if you hear any leaks.

Gotchaaa.

What don't you like about the P3?

[mkPOTO]

Originally Posted by Compman

Gotchaaa.

What don't you like about the P3?

I just emailed them about the problem. But it seems that my current tune was not uploading correctly as the P3 gauge was blocking a few lines of code. So it would randomly throw codes. I uninstalled it and it drove and had no codes.

[Compman]

Originally Posted by mkPOTO

I just emailed them about the problem. But it seems that my current tune was not uploading correctly as the P3 gauge was blocking a few lines of code. So it would randomly throw codes. I uninstalled it and it drove and had no codes.

Oh wow that's crazy

[Longboarder]

Wow hope you get it figured out. Should be low 11's at high 120's on decent street tires once sorted.

[L4ces]

Think positive for a positive outcome. You will be one happy camper to go from the stock feel to fully boosted after tightening something up that is simple.
Almost like instant gratification.

[Properstyle]

Your boost leak is likely at the throttle bodies where the intake sits. It has happen to me before where the intake lifted out of the couplers I had to reseat it and tighten the clamps. After that car was at 7 psi again. Your 1/4 miles time is what my m3 did on motor.

[Patrón]

it's my estimate that your vacuum at idle is way to high. mine is 11-13 depending on the weather. reroute everything to the bypass valve as mentioned and make sure you are not leaking anywhere. the bypass needs pressure to close the valve for full boost. you can also check the setting/bolt on the bypass valve but that would be a last resort.

[Compman]

Do I have to drain the manifold to reseat it??

Is there a diagram for the vacuum line routing of the supercharger & by pass valve.

Also what's the proper adjustment of the by pass valve??


Does anyone else's super charger puke out a little bit of oil on a hot day and a spirited run??

Okay I'm thinking positive!! I'm so excited to feel this monster. It's going to be crazy!!!!


Thanks for the help and support again. I don't know what I would do without this forum!!